Hard materials at hand are for example materials such as granite, marble, concrete, asphalt, brickwork, ceramics, mixed ceramics, or ceramic glasses. Generally, hard materials at hand are materials which promote the abrasion—that is the abrasion of tools—to a considerable extent. Due to the abrasive properties, these materials are therefore often machined by means of geometrically undetermined blades—for example by grinding.
From DE 100 24 129 C1 and from EP 0 922 551 A2 are already known methods for machining rock where a material removal takes place by means of geometrically determined blades in the form of a milling process. With these known methods, an impact mechanism is used respectively, where a radial impact frequency is induced by an integrated pendulum or wobble tube. These methods can however only be used when a coarse surface of the machined surface can be accepted.
In particular, considerably higher demands are made of the surface quality when machining ceramics, mixed ceramics or ceramic glass, which up to now are only achieved by the known methods by means of a geometrically undetermined blade such as grinding. These machining methods are often implemented using a coolant and/or a lubricant. The fact that residues of these operating fluids often remain near the surface within the hard material is disadvantageous. This can lead to allergic reactions in the patient, for example, in the medical or dental sector.
In US 2004/170480 A1 is disclosed a tool for machining a material that is difficult to remove, for example, a heat-resistant alloy or stainless steel where the blade is geometrically determined and comprises a blade angle of less than 10°.
The article by C. Yalcin, B. K Fussell, Y. Erzan and E. B. Jerard: “Real-time calibration of cutting forces model for CNC milling”, found on the internet under the URL: http://www.unh.edu/dml/publications/2004/UL—030—2004.pdf, Proceedings of 2004 JUSFA—2004 Japan—USA Symposium on Flexible Automation, Denver, Colo., Jul. 19-21, 2004 describes a detailed model for cutting forces with CNC machines.